A novel left ventricular (LV) mapping system (Biosense, Inc.) uses low- intensity magnetic field energy to determine the location of sensor- tipped catheter electrodes within the LV. On the basis of previous experimental and human studies correlating the extent of myocardial ischemia with the amplitude of electrical signals, we hypothesize that such an integrated LV electromechanical mapping system could be used to distinguish healthy from ischemic or immobile myocardium on the basis of the extent of electromechanical endocardial signals. If this hypothesis is confirmed, the ability to detect on-line myocardial viability and ischemia in the catheterization laboratory may be feasible.The present study attempts to distinguish between ischemic, immobile, and normal myocardium by comparing LV electromechanical mapping data at rest and during pharmacologic stimulation, with imaging studies using MRI, PET, thallium and echo in patients with coronary artery disease.Once this technique is perfected as a guidance tool within the LV, we will embark on studies using this delivery system for laser revascularization and direct injection of angiogenic vectors. - Myocardial viability, ischemia, PET, MRI, electromechanical endocardial mapping - Human Subjects